About a week ago, I felt a notable jerk mid-acceleration. Check engine light had come on earlier in the day. I've had my fair share of trips to the dealer for repairs and wasn't alarmed by a silly check engine light. Got to the house and checked codes and has P0171 and P0420. By this time, idle was now slightly rough.
I replaced my spark plugs on Saturday with Iridium replacements. Sunday, car ran like pooh! Severe jerking under acceleration (more like refusal to accelerate). Changed the the plugs back to original factory plugs and car became derivable (less pooh). Read forums (thanks for tips) and followed some leads.
Monday, picked up a valve cover at the dealer ($69.00) after noticing, or rather felt, blazing hot gases escaping the PCV valve's ambient air vent. Checked the previously removed new spark plugs for gap to discover they were nowhere near .025~.028. I set plugs aside for the time being and replaced the valve cover and cleared the codes.
Now, car runs like pooh, but smoother under very, very light acceleration. Mid to hard acceleration (as in gas pedal press) is still jerky with nonexistent velocity improvement. To accelerate, I have to keep throttle below 30-ish percent. This evening I changed the pugs after I gaped them to .026~.028.
What I have now is a car that runs poorly (being polite, poorly is an understatement) and with no check engine light or codes.
My Cruze: 2011 1LT, Ice Silver, Connectivity package, Allow wheels, 106,000 miles, 2nd set of tires, 12th oil change - always approved synthetic, and warranty is over!
Any assistance would be greatly appreciated.